1. Field of the Invention
The present invention relates to imaging systems. More specifically, the present invention relates to techniques for detecting a change in an image from one frame to another and either compensating therefor or providing an output signal indicative thereof.
While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility.
2. Description of the Related Art
There are many applications in which it is desirable to detect motion of or within an image from one frame to the next. For example, it is well known in the art that certain conventional electro-optical systems experience jitter due to platform vibration which causes a degradation in image quality. While many image compensation techniques exist in the art for correcting for such jitter, there are numerous disadvantages associated with each. Conventional image compensation techniques include accelerometer oriented and gimbal oriented techniques. The accelerometer oriented techniques use an accelerometer to detect motion of the platform. The accelerometer generates control signals which are used to correct for vibration in the platform. The correction may be performed electronically or by adjustments in the optical train. Accelerometer oriented techniques are somewhat effective in controlling jitter. However, these systems are generally costly, unreliable, and have certain performance limitations, i.e., the ability to correct in multiple directions and in response time.
In gimbal oriented systems, the optical system is mounted on gimbals for stabilization. In addition to being costly, these mechanical systems are also generally cumbersome and heavy.
Another application for image motion detection is in security systems where there is a need to detect the movement or entry of something within an area of surveillance. Conventional techniques for image tracking involve the use of tracker algorithms such as the Fitts correlation tracker algorithm. Unfortunately, these algorithms are often computationally intensive and therefore somewhat slow. In addition, some algorithms, such as the Fitts algorithm, are limited with respect to the ability to perform subpixel tracking and to track multiple pixel movements.
Accordingly, there is a need in the art for a fast, inexpensive, and reliable image motion tracking system.